Taxon name
Thalasseus bergii
(Lichtenstein, 1823)
Uploaded by
National Red List Database
Taxonomic information
Scientific name
Thalasseus bergii
(Lichtenstein, 1823)
Assessed taxon level
Species
Higher level taxonomic groupings
Vertebrates
Birds
Species authority
(Lichtenstein, 1823)
Taxonomic notes and synonyms listed
Thalasseus bergii (del Hoyo and Collar 2014) was previously placed in the genus Sterna.
Location and scope
Specific locality or subnational name or regional name
United Arab Emirates (the)
Scope (of the Assessment)
National
Countries included within the scope of the assessment
United Arab Emirates (the)
Does the assessment cover a marine EEZ area(s)?
Not_assigned
Conservation Status
Assessed as
Near Threatened
Qualifying criteria (if given)
D2
Criteria system used
IUCN
(see Assessment details)
Assessment rationale/justification
This species has a moderate breeding population in the UAE of 2,700-3,000 mature individuals. The species is known to currently nest on only one island (Qarnayn Island), with evidence of breeding on Sir Abu Nair to be confirmed. On Qarnayn Island, the impact of introduced predators is significant. However, the species is stable within the country and in the wider Arabian Peninsula and there is no evidence of continuing decline in population, AOO or quality or extent of habitat in the UAE. The species is assessed as Vulnerable (D2). However, the potential for immigration from outside the UAE remains very high. Therefore, the species is listed as Near Threatened at the national level.
Assessment details
Assessors/contributors/reviewers listed
UAE National Red List Workshop
Criteria system used
IUCN
Reference for methods given
IUCN. 2012. IUCN Red List Categories and Criteria: Version 3.1, Second edition. IUCN, Gland, Switzerland and Cambridge, UK. iv + 32pp pp. And IUCN. 2012. Guidelines for Application of IUCN Red List Criteria at Regional and National Levels: Version 4.0. Gland, Switzerland and Cambridge, UK: IUCN. iii + 41pp.
Further information
Endemism (according to assessment)
Endemic to region
Not assigned
Taxon distribution as listed in assessment
The majority of occurrences of this species is likely to be of migrant individuals on passage to and from the breeding grounds and of wintering birds along the coast of the UAE (Pedersen et al. 2017). Additionally, the species is a rare breeding visitor on Qarnayn;Island, with breeding on Sir Abu Nair to be confirmed. It breeds between March and November (Jennings 2010, Pedersen et al. 2017).
Is there a map available in assessment?
Yes
Habitat and systems
Ecological system type
Habitat
Habitat details as listed in assessment
This species occurs on the open sea up to 50 km off the coast, and only comes to offshore islands or to the mainland for resting on sandy beaches (Jennings 2010, Aspinall and Porter 2011). It forages in small groups by plunge-diving or surface-dipping (Jennings 2010). There is no information available about its diet in the UAE; elsewhere, it feeds predominantly on small pelagic fish, but it will opportunistically take cephalopods, crustaceans, insects and hatchling turtles (Urban et al. 1986, del Hoyo et al. 1996, Higgins and Davies 1996). The species also preys on chicks of White-cheeked Tern Sterna repressa and Lesser Crested Tern Thalasseus bengalensis (Jennings 2010). The species breeds in spring to early summer; in the UAE, eggs have been recorded between May and June (Jennings 2010). It breeds on offshore islands in large dense colonies of up to 1,000 pairs, often associated with Lesser Crested Tern Thalasseus bengalensis and other tern species (Jennings 2010). The colonies are located on open, sandy areas (Jennings 2010). On Qarnayn;Island, the nesting habitat is in the soft sandy areas on the northwestern part of the island. A single egg is laid on the bare sand; only during incubation and nestling stage, a shallow scrape develops (Jennings 2010). Juveniles leave the nests a few days after hatching and form crèches along the shoreline (Jennings 2010). After the breeding season, individuals breeding off the UAE coast migrate south as far as the coast of Kenya, while birds from the northern Arabian Gulf may winter in the UAE (Jennings 2010).
Threats and conservation measures listed
Threats listed in assessment
On Qarnayn;Island, threats include predation by rats and cats. Aspinall (1996) identifies the key threats to this species as egg collecting, invasive mammals, development, disturbance and pollution (e.g. from oil, and other chemicals). The severity of these threats, however, is uncertain.
History
It is thought that the species previously nested on two islands with restricted EOO and AOO and qualifying as two locations. At the time it would not have been deemed that threats could have driven the species Regionally Extinct or Critically Endangered in a short period of time and so the species is thus backcast as Near Threatened in 1996, downlisted with a regional adjustment to Least Concern as a result of the substantial potential for immigration from outside the UAE. With the species now restricted to just one location, threats are now deemed to be able to drive the species Regionally Extinct or to Critically Endangered within a short period of time; hence its current listing as Near Threatened (regionally adjusted down from Vulnerable).
Publication
Burfield, I.J., Westrip, J., Sheldon, R.D., Hermes, C., Wheatley, H., Smith, D., Harding, K.A. Allen, D.J. and Alshamsi, O. 2021. UAE National Red List of Birds. Ministry of Climate Change and Environment, Dubai, United Arab Emirates
